Overweight places over one-fourth of U.S. women at risk for poor health and increased mortality. Longitudinal studies of the effect of pregnancy on body weight that control for the confounding effect of age have found an average weight retention of approximately 2.2 pounds per birth. The Institute of Medicine suggests that this figure may underestimate weight retention associated with the higher gestational weight gains seen in recent years. Effective obesity prevention and intervention requires an indepth, cross- disciplinary understanding of postpartum weight retention. The proposed research will describe and quantify the inter-relationships between biological, behavioral, psychological, and sociodemographic characteristics of women and their joint and separate relationships to postpartum weight retention. This will be accomplished through three complementary studies designed to overcome the limitations inherent in any single scientific research approach. The first study is a qualitative examination of behavioral and psychological factors. A purposive sample of 40 women will be followed from the second trimester of pregnancy to one year postpartum. It is designed to provide an indepth understanding of how the role and life- style changes associated with childbearing are related to postpartum weight retention and how they act to mediate relationships between sociodemographic factors. The second study is a secondary data analysis of NHANES designed to quantify the extent to which sociodemographic characteristics are related to postpartum weight retention in nationally representative samples of women. This study will also examine the extent to which the behavioral factors of energy intake, physical activity and smoking relate to postpartum weight retention and mediate the relationship of sociodemographic factors. The third study is an observational prospective community-based study of a final sample of 450, rural women followed from mid-pregnancy to two years postpartum. It will examine sets of biological, behavioral, psychological and sociodemographic factors in an integrative fashion and result in quantitative predictive models of postpartum weight retention. Taken together, the results will enable health care providers to identify women who are at higher risk for postpartum weight retention and to recommend strategies to help them manage their weights.